Bitcoin may be risky, but its jump to another new high has been nothing short of "amazing," closely followed strategist Bob Doll told CNBC on Monday.

The cryptocurrency surged to a record $9,682.10 on Monday, according to CoinDesk, breaking a mark set during Thanksgiving weekend. It later retreated to $9,615.13. It has risen more than 850 percent this year.

"'With bitcoin, why do you need the stock market?' has been the saying of late," said Doll, Nuveen Asset Management's chief equity strategist.

"I confess it's an area of that to me feels speculative, but you might call me old or old-fashioned. It's been an amazing run, has it not?" Doll added in an interview on "Worldwide Exchange."

Bitcoin has hit new records several times this year, though not everyone on Wall Street favors the cryptocurrency. JPMorgan Chase CEO Jamie Dimon has called it a fraud" and said investors will ultimately "pay the price for it."

Expect 'bump' on tax-reform worries

With the Senate moving toward a vote this week on GOP's tax reform bill, Doll said investors are closely watching the developments.

"I suspect there will be some moments where it's not going to happen," Doll said. "That could create a little bump in the market, but I believe we'll get a bill done early next year."

On CNBC's "Squawk Box," Morgan Stanley chief U.S. economist Ellen Zentner said the promise of tax reform is "better than the delivery."

"Either it's a sell on the news event early next year or its disappointment because Congress didn't do what folks thought they would do," she said.

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